54 lines
1.7 KiB
Go
54 lines
1.7 KiB
Go
package sign
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import (
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"fmt"
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"strings"
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)
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func (context *SignContext) updateByteRange() error {
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if _, err := context.OutputBuffer.Seek(0, 0); err != nil {
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return err
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}
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output_file_size := int64(context.OutputBuffer.Buff.Len())
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// Calculate ByteRange values to replace them.
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context.ByteRangeValues = make([]int64, 4)
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// Signature ByteRange part 1 start byte is always byte 0.
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context.ByteRangeValues[0] = int64(0)
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// Signature ByteRange part 1 length always stops at the actual signature start byte.
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context.ByteRangeValues[1] = context.SignatureContentsStartByte - 1
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// Signature ByteRange part 2 start byte directly starts after the actual signature.
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context.ByteRangeValues[2] = context.ByteRangeValues[1] + 1 + int64(context.SignatureMaxLength) + 1
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// Signature ByteRange part 2 length is everything else of the file.
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context.ByteRangeValues[3] = output_file_size - context.ByteRangeValues[2]
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new_byte_range := fmt.Sprintf("/ByteRange [%d %d %d %d]", context.ByteRangeValues[0], context.ByteRangeValues[1], context.ByteRangeValues[2], context.ByteRangeValues[3])
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// Make sure our ByteRange string didn't shrink in length.
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new_byte_range += strings.Repeat(" ", len(signatureByteRangePlaceholder)-len(new_byte_range))
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if _, err := context.OutputBuffer.Seek(0, 0); err != nil {
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return err
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}
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file_content := context.OutputBuffer.Buff.Bytes()
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if _, err := context.OutputBuffer.Write(file_content[:context.ByteRangeStartByte]); err != nil {
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return err
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}
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// Write new ByteRange.
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if _, err := context.OutputBuffer.Write([]byte(new_byte_range)); err != nil {
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return err
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}
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if _, err := context.OutputBuffer.Write(file_content[context.ByteRangeStartByte+int64(len(new_byte_range)):]); err != nil {
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return err
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}
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return nil
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}
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